For plumbing layout, carry an 8 oz brass plumb bob such as the Stanley 47-973 and a 100 foot chalk reel such as the Tajima CR202B-P, which snaps a thin 0.5 mm line. For bold lines on rough slab, the Milwaukee 48-22-3982 kit with blue chalk is the better reel, and the 16 oz Empire 916BR steadies tall or drafty drops; buy those two from a dealer, because we found no in-stock Amazon listing for either. Use blue or white chalk indoors, because the makers say red and black are permanent.
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A plumb bob is how you put a floor hole straight under a ceiling mark, and a chalk line is how you keep a long pipe run straight. Both start with good measurements; see our guide to toilet rough-in size for the most common one.
Plumb bobs and chalk lines compared
| Check | Stanley 47-973 | Empire 908BR | Empire 916BR | Milwaukee 48-22-3982 | Tajima CR202B-P |
|---|---|---|---|---|---|
| Type | Plumb bob | Plumb bob | Plumb bob | Chalk line kit | Chalk reel |
| Weight or line | 8 oz (225 g) | 8 oz | 16 oz | 100 ft braided bold line | 100 ft, 0.02 in (0.5 mm) line |
| Body or case | Solid brass, lacquered | Solid brass, lacquered | Solid brass, lacquered | Rubber overmold | Aluminum case, gasket-sealed die-cast body |
| Tip or drive | Replaceable hardened steel tip, extra tip | Extra hardened steel tip included | Extra hardened steel tip included | 6:1 gear retraction, planetary gears | Five-gear drive |
| Line attach or extras | Screw top centers the string | Ties to any string or line | Ties to any string or line | Blue chalk, StripGuard clutch | Gasket-sealed refill port |
| Choose when | One bob for indoor drops | Brass bob from a level maker | Tall drops, drafty spaces | Fast rewind, bold lines | Thin, precise lines |
| Exact purchase | Check Stanley 47-973 on Amazon → | Buy from an Empire dealer; we found no in-stock new Amazon listing on October 14, 2026. | Buy from an Empire dealer; we found no in-stock new Amazon listing on October 14, 2026. | Buy from a Milwaukee dealer; we found no in-stock new Amazon listing for this blue-chalk kit on October 14, 2026. | Check Tajima CR202B-P on Amazon → |
Specs are from the Stanley 47-973 page (maker page: www.stanleytools.com/en-us/product/47-973/8-oz-225g-brass-plumb-bob), the Empire plumb bob page (empirelevel.com), the Milwaukee 48-22-3982 page (milwaukeetool.com) and the Tajima CR202B-P page (maker page: www.tajimatool.com/product/cr202b-p/). Milwaukee’s spec tab did not load when we read it, so line diameter and chalk capacity are not listed here.
BEST PLUMB BOB FOR PLUMBERS · 8 OZ BRASS, SCREW TOP
Stanley 47-973: best plumb bob for plumbers
Choose it when you want one bob for indoor drops from ceiling to floor. Stanley lists the 47-973 as an 8 oz (225 g) bob with polished, lacquered solid-brass construction, a replaceable hardened steel tip with an extra tip included, and a screw top that attaches the string at the center of the bob, on the 47-973 page (maker page: www.stanleytools.com/en-us/product/47-973/8-oz-225g-brass-plumb-bob). Stanley’s spec line says steel while the features say solid brass, so read the listing if the material matters to you.
The screw top is the feature that matters. A string tied off center makes the bob hang crooked, and the point lands a little off. A center attachment keeps the point right under the string.
Skip it if you drop through two floors or work in a drafty attic. A heavier bob moves less in moving air.
BRASS BOB · 8 OZ, EXTRA TIP
Empire 908BR: 8 oz brass plumb bob
Choose it when you want a plain brass bob with a spare tip. Empire lists the 908BR as an 8 oz solid brass plumb bob with a lacquered finish to resist corrosion, an extra hardened steel tip included and a 1 year limited warranty, on the Empire plumb bob page (empirelevel.com). Empire says it ties easily to any string or line. Replacement tips are sold separately as part 90832.
Empire also makes steel bobs, the 905 at 5 oz and the 908 at 8 oz, with a plated finish. Brass is the better pick for a plumber because it does not rust in a damp crawl space.
Skip it if you want a screw-top string attachment. Empire does not describe one on its page, and the Stanley 47-973 has it.
Buy from an Empire dealer; we found no in-stock new Amazon listing on October 14, 2026.
HEAVY BOB · 16 OZ BRASS
Empire 916BR: 16 oz plumb bob for long drops
Choose it when your drop is tall or the air moves. Empire lists the 916BR as a 16 oz solid brass bob with a lacquered finish and an extra hardened steel tip, on the Empire plumb bob page (empirelevel.com). Empire makes the same bob in 12, 24 and 32 oz, though the 32 oz 932BR does not include an extra tip.
Twice the weight pulls the string tighter and gets pushed around less by moving air. That helps on a two-story vent chase, in an open stairwell, or outside where wind pushes the line.
Skip it if most of your drops are 8 or 9 foot ceilings indoors. A 16 oz bob takes longer to stop swinging by hand and is heavier in the bag.
Buy from an Empire dealer; we found no in-stock new Amazon listing on October 14, 2026.
BEST CHALK LINE KIT · 100 FT, 6:1 REWIND
Milwaukee 48-22-3982: best chalk line kit
Choose it when you snap long pipe runs on slab, subfloor or framing. Milwaukee lists the 48-22-3982 kit with a 100 foot high-strength braided bold line, blue chalk, a 6:1 gear retraction ratio with a planetary gear system, flush handle storage, a rubber overmold and a StripGuard clutch, on the 48-22-3982 page (milwaukeetool.com).
A bold line is easy to see on rough concrete and OSB, which is where plumbers snap most lines: a trench line on a slab before cutting, or a pipe run across joists. The fast rewind matters when you snap the same line many times along a long run.
Skip it if you need a thin, exact line on a smooth surface. A bold line leaves a wide mark, and the Tajima below leaves a finer one.
Buy from a Milwaukee dealer; we found no in-stock new Amazon listing for this blue-chalk kit on October 14, 2026.
FINE-LINE CHALK REEL · 0.5 MM LINE
Tajima CR202B-P: fine-line chalk reel
Choose it when precision matters more than visibility. Tajima lists the Chalk-Rite II Ultra-Thin CR202B-P with a 0.02 inch (0.5 mm) braided line, 100 feet long, a five-gear winding drive, a heavy-duty aluminum case with a gasket-sealed die-cast body and a large gasket-sealed refill port, on the CR202B-P page (maker page: www.tajimatool.com/product/cr202b-p/).
A thin line gives a sharper mark to cut to, which helps when you lay out a row of floor penetrations or a straight line for a trench drain or a run of hangers. The sealed body helps keep chalk dry in a damp basement.
Skip it if you snap mostly on rough slab outdoors. Tajima does not list chalk included on this page, and a thin line can be hard to see on coarse concrete. Tajima also makes Extra Bold Chalk-Rite models such as the CR201R-PR.
How to transfer a drain or vent center
The common job is putting a floor hole straight below a point on the ceiling, or a top plate hole straight above a drain. Here is how to do it with a bob.
- Mark the center point on the ceiling or the underside of the top plate. Drive a small nail or screw at the mark, or use a hook.
- Tie the string to the bob’s top so it hangs at the center. On a screw-top bob, thread it through the cap.
- Hang the bob from the nail and let it drop to within about 1/4 inch of the floor.
- Steady the swing with your fingers, then let go and wait until the point stops moving.
- Mark the floor right under the point. Make a small cross so you can still see the center after you start a pilot hole.
- Check the mark against your fixture layout before you core or cut. Measure to finished walls, not studs.
On a slab, coring or chipping for a drain is a rotary hammer job. Check for post-tension cables, radiant tubing and buried lines first, and stop and call the engineer if you find tendons or tension markings.
Choosing plumb bob weight
Weight is a trade-off between speed and steadiness. A light bob is quicker to settle by hand in still air and is easy to carry. A heavy bob holds the string tighter and moves less in a draft, but it swings longer once it gets going.
- 5 to 8 oz: standard rooms with 8 to 10 foot ceilings and no air movement. This is the size most plumbers carry.
- 12 to 16 oz: two-story chases, stairwells, attics with ventilation, or outdoor work.
- 24 to 32 oz: very tall drops or windy sites. Heavy for a tool bag.
Pick a bob with a hardened, replaceable tip. A bent or dull tip puts the mark in the wrong spot. All three bobs picked here come with a spare hardened steel tip.
Snapping pipe runs and choosing chalk color
How to snap a clean line
- Mark both ends of the run. On long runs, add a mark in the middle to check for sag.
- Hook the line on one mark, or have a helper hold it.
- Pull the line tight across the other mark and hold it down flat.
- Lift the line straight up from the middle a few inches and let it snap. Do not pull it sideways.
- Rewind and recharge with chalk between long snaps so the line stays bold.
Chalk color
| Color | IRWIN says | STANLEY says | Use it for |
|---|---|---|---|
| Blue | Non-permanent; can wash away, but can be permanent on some surfaces | Temporary | Most layout on subfloor, slab and framing |
| White | Recommended for indoor use when possible | Temporary | Finished floors and walls where marks must come off |
| Red | Permanent, nearly impossible to remove | Permanent | Outdoor or rough work where the line must survive weather |
| Black | Permanent | Permanent, the most permanent | Long-term marks on concrete or rough framing |
| Orange, green, yellow | Permanent | Not addressed | Only where a permanent line is fine |
Color guidance is from IRWIN support (support.irwin.com) and STANLEY support (maker page: support.stanleytools.com/hc/en-us/articles/360012680358-What-do-I-use-to-remove-my-chalk-line). STANLEY says a chalk line mark is meant to stay and it knows of no way to remove it, so test on scrap or in a hidden spot before you snap across a finished floor. On finished surfaces, a pencil and a straightedge may be the better call.
A plumb bob and chalk line both fit in a small pouch in a plumber’s tool backpack.
Plumb bob and chalk line FAQ
What is a plumb bob used for in plumbing?
A plumb bob hangs a pointed weight on a string to find a point straight below another point. Plumbers use it to put a floor or slab hole straight under a ceiling or top plate mark for a drain or vent.
What weight plumb bob should I buy?
An 8 oz bob covers most indoor drops with standard ceilings. Choose 12 to 16 oz for tall drops, drafty spaces or outdoor work, because the heavier weight moves less in moving air.
Which chalk color is not permanent?
IRWIN calls blue chalk non-permanent but says it can be permanent on some surfaces, and recommends white indoors. IRWIN and STANLEY both say red and black are permanent.
Is a brass or steel plumb bob better?
Brass resists corrosion and is the better pick for damp crawl spaces and basements. Empire and Stanley both sell lacquered brass bobs with hardened steel tips.
How do I keep a chalk line from smudging?
Pull the line tight, hold both ends flat, and lift it straight up from the middle before you let it snap. Do not pull it sideways, and recharge the chalk between long snaps.
How we chose
This is a document-based roundup from a licensed plumber’s point of view. We read the maker product pages for each exact linked plumb bob and chalk line, plus IRWIN and STANLEY support pages on chalk color. We picked brass bobs with hardened, replaceable tips and chalk reels with published line length and gearing. Sources and linked listings were read October 14, 2026; sellers and availability change. We do not publish prices or claim hands-on testing. More about our selection method and Plumbing Picks.
Primary sources
- Stanley 47-973 8 oz brass plumb bob (maker page: www.stanleytools.com/en-us/product/47-973/8-oz-225g-brass-plumb-bob): weight, brass body, replaceable tip, screw top.
- Empire plumb bobs (empirelevel.com): 908BR, 916BR and other weights, materials, extra tips, warranty.
- Milwaukee 48-22-3982 100 ft Bold Line kit (milwaukeetool.com): line, blue chalk, 6:1 gear ratio, features.
- Tajima CR202B-P Chalk-Rite II Ultra-Thin (maker page: www.tajimatool.com/product/cr202b-p/): line diameter and length, five-gear drive, sealed case.
- IRWIN support on chalk color (support.irwin.com): permanent and non-permanent colors.
- STANLEY support on removing chalk lines (maker page: support.stanleytools.com/hc/en-us/articles/360012680358-What-do-I-use-to-remove-my-chalk-line): temporary and permanent colors.
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